Concept map options for maintaining blood pressure can lower blood volume, causi

Question

Concept map options for maintaining blood pressure

can lower blood volume, causing baroreceptors to activate cardioaccelatory center epinephrine, NE, ADH, and angiotensin can increase blood return, increasing stimulate(s) sympathetic -volume and venous peripheral resistance (PR) fibers, increasing cardiac output (CO) cause(s) blood pressure vasoconstriction, directly increasing reduced ANP output skeletal muscle activity bleeding or sweating if high, when combined with high PR, increase(s) if high, when combined with high Co, increase(s)

Explanation / Answer

Blood pressure is affected by several factors

• peripheral resistance

• vessel elasticity

• blood volume

• cardiac output

Role of Angiotensin in Blood Pressure(Renin-Angiotensin System)

Renin is a protein enzyme released by the kidneys when the arterial pressure falls too low. In turn, it raises the arterial pressure in several ways , thus helping to correct the initial fall in pressure.

Renin is stored in inactive form called prorenin in the juxtaglomerular cells(JG-Cells) of the kidneys. Renin itself is an enzyme not an vasoactive agent. The renin persists in the blood for 30 minutes to 1 hour and continues to cause formation of still more angiotensin-1 during this entire time.

Angiotensin-2 has two principal effects that can elevate arterial pressure. The first of these, vasoconstriction in many areas of the body, occurs rapidly.The second principal means by which angiotensin-2 increases blood pressure is to decrease excretion of both salt and water by the kidneys.

Angiotensin-2 causes the kidney to retain both salt and water in two major ways:

1. Angiotensin-2 acts directly on the kidney to cause salt and water retention.

2. Angotensin-2 causes the adrenal gland to secrete aldosterone , and the aldosterone in turn increases salt and water reabsorption by the kidney tubules.

Baroreceptor Reflex:

By far the best known of the nervous mechanism for arterial pressure control is the baroreceptor reflex. Basically, the reflex is initiated by the stretch receptor, called either baroreceptor or pressoreceptor, located at specific points in the wall of several large systemic arteries. A rise in arterial pressure stretches the baroreceptor and cause them to transmit signals into central nervous system(CNS), 'Feedback' signals are then sent back through the autonomic nervous system to the circulation to reduce arterial pressure downward towards the normal level.

Peripheral Resistance:

If high blood pressure combined with high peripheral resistance, increases the blood pressure. Peripheral resistance accounts for the resistance that the blood vessels applies to the blood flowing through it.

Cardiac Output:

Cardiac output is the amount of blood pumping out of the heart in each beat of the heart that last for around 0.8seconds. High cardiac output is definitely going to increase the blood pressure.

Bleeding and sweating causes vasoconstriction directly increasing the blood pressure.

Atrial Natriureticpeptide(ANP) inhibit renin secretion, thereby inhibiting the renin-angiotensin-aldosterone system. Agiotensin causes (1.) renal retention of salt and water (2.) vasoconstriction , which in turn causes increased arterial blood pressure. But if reduced ANP is there in body then it can cause increased blood pressure.

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